#include<iostream>
using namespace std;

int main()
    int n;
    cin>> n;
    
    if(n <=0) cout<< "Invalid input";
    else if (n >12) cout<< "Over4flow occured.";
    else {
        long long f=1;
        for(int i=1; i<=n; i++) f*=i;
        cout <<f;
    }
        
    }